After completing the 32T all-superconducting user magnet, development of magnets of this class with a noticeably higher field has begun: the NHMFL 40T magnet is the immediate target. The next generation of high temperature superconductor (HTS) high-field user magnets demands the next generation of quench protection systems. Previously, a bank of batteries was employed to power the quench...
Quench protection is one of the key issues for superconducting magnets with high energy storage, especially for those wound with superconducting cables, which have low thermal conductivity between each turns. Thermal quench-back induced by a co-wound heater wire is an available quench protection scheme for the magnets wound with 6+1 type cables (6 superconducting wires wound with 1 heater...
Use of 2G HTS superconductors in magnet applications allows creating compact magnets with large magnetic fields due to many times higher current density of superconductors in comparison with traditional metal wires. At the same time, 2G HTS tapes make the design of magnet special and require choosing 2G HTS tape parameters suitable to each magnet design. The unique properties of 2G HTS tapes...
Protecting a high temperature superconducting (HTS) magnet from a quench event is a challenging task, especially in the case of accelerator magnets where current density is usually very high. Because of the slow normal zone propagation velocity, the long reliable quench detection method by coil voltage may not be timely for HTS anymore, leaving HTS magnets under danger of overheating. Many new...
The authors’ group is investigating a quench protection method for HTS coils that use Cu tape co-wound with HTS tape. In this method, the voltage $V_s$ across the resistive zone in the HTS coil is monitored by measuring the voltage difference between the HTS coil and the co-wound Cu tape coil in normal operation. When $V_s$ exceeds the quench detection voltage, the HTS coil is disconnected...
In the framework of a joint collaboration funded by US Department of Energy (DOE), a large bore “Cable Test Facility Magnet” is under development. This is a joint effort between the Office of High Energy Physics (HEP) and the Office of Fusion Energy Sciences (FES). A 15 T Nb3Sn dipole magnet is being developed at Lawrence Berkley National Laboratory (LBNL). The magnet will produce the...
We have been developing the Frequency Loss Induced Quench (FLIQ) protection system for high-temperature superconducting magnets. We have studied the sensitivities of the various FLIQ system parameters to understand the design of an effective quench protection system. FLIQ drives AC current in the magnet coil and generates AC losses. The heating associated with the losses quenches the HTS...
Here we have studied the performance and quench properties of a large (outer diameter: 901 mm; winding pack: 44 mm thick × 50.6 mm high) conduction-cooled, react-and-wind, MgB2 superconducting coil. Minimum quench energy (MQE) values were measured at several coil operating DC currents (Iop ), and distinguished from the minimum energy needed to generate a normal zone (MGE). During these...
Superconducting magnet protection must address two main areas of the magnet and circuit performance, namely Conductor Hot-Spots and Circuit Voltages. Both hot spot and voltage operational maximums are during the superconductor's transition called a Quench. Historically high voltages have resulted in many damaged and destroyed magnet coils so reducing voltages is a preferred direction for...
The main challenges to implementing HTS in ultra-high field are management of stress and quench, due to intrinsic strain limits and lower normal zone propagation velocities than LTS magnets. While Bi-2212 magnets can be considered comparatively easier to protect than ReBCO coils due to Bi-2212’s more moderate margin and high silver stabilizer fraction, quench management is critical when moving...
Metal plates are applied in high-temperature superconducting (HTS) magnet to provide a mechanical support and conduction cooling. The electromagnetic coupling between the metal plates and HTS coils has a considerable influence on the discharge operation of HTS coils during quench protection. In this paper, a multi-physics model is developed using circuit- field coupling method to study the...
